I would prefer the site to be Joomla based since I am already familiar with the Joomla set up in terms of site editing etc.
This is a Business-to-business site that will not require any payment gateway for downloads, but users must be restricted to see only the downloads that they have paid for. In addition, there needs to be a mechanism for counting the number of times each corporate user downloads an item as this is how they will be invoiced.
There will be a number of downloadable items help on an FTP server, but users will only have access to the ones they pay for, so security is essential.
I have an existing site that uses Joomla for hypnosis downloads that you can have a look at [url removed, login to view] to see how it works. This new site needs only the download capability, so no need to use it in conjunction with Virtuemart.
I have some ideas for design, and a domain name so you need to either be good at design or have access to a designer.